Desperate Noobie...
Hi Chris,
Saw this thread and thought I'd extend a shameless plea for help - I have a 510M with a dead left channel. Boy, when these things fail, they fail BIGTIME - all drivers and outputs are shorted. 🙁 I've got subs for the TO-3 outputs, but I'm coming up completely empty on the smaller TO-66 drivers. Do you have any recommendation for subs on these? 😕 I'd be happy to donate to the site in return for your help...
anatech said:
Hi Chris,
Saw this thread and thought I'd extend a shameless plea for help - I have a 510M with a dead left channel. Boy, when these things fail, they fail BIGTIME - all drivers and outputs are shorted. 🙁 I've got subs for the TO-3 outputs, but I'm coming up completely empty on the smaller TO-66 drivers. Do you have any recommendation for subs on these? 😕 I'd be happy to donate to the site in return for your help...
Hi dbp650,
I don't think donations would ever be turned down by admin. 😉
Now to your problem. The TO-66 parts can be replaced by the TO-220 case devices. The TO-220 was actually designed to be a plastic replacement for the TO-66. Try MJE15034 and MJE15035.
Now for the rest of your troubles that you may not know about yet. 😱 You need to add an insulating, non-compressable spacer between the busses and the heatsink. Retain the original spacers so they will act as bushings. The thickness is 1/10" if I remember correctly. That will keep the outputs from loosening off when they get hot.
Now the reason for the heat. All the box capacitors need to be replaced. Those are bypass caps and they go open. Change the zobel cap and check the zobel resistor.
You must match all the driver and output transistors. It's important. Buy only new. If you have bought NTE or ECG's, pitch them as they are hopeless. Give them to someone you don't like.
I'm going to bet the amp was oscillating and cooked itself to death. I found out about this from a repair. The channel powered up fine, bias and offset was stable so I went to get a coffee (Hey! I'm a technician, what else do you expect?). Coming back I could smell the heat, the scope had a fully lit screen from the rather strong oscillation. Pulling the caps and testing them, I found most were next to open. The point I'm making is that it may not break into oscillation right away.
If you use a variac to bring the voltage up slowly, you need to short the surge resistor out first.
-Chris
I don't think donations would ever be turned down by admin. 😉
Now to your problem. The TO-66 parts can be replaced by the TO-220 case devices. The TO-220 was actually designed to be a plastic replacement for the TO-66. Try MJE15034 and MJE15035.
Now for the rest of your troubles that you may not know about yet. 😱 You need to add an insulating, non-compressable spacer between the busses and the heatsink. Retain the original spacers so they will act as bushings. The thickness is 1/10" if I remember correctly. That will keep the outputs from loosening off when they get hot.
Now the reason for the heat. All the box capacitors need to be replaced. Those are bypass caps and they go open. Change the zobel cap and check the zobel resistor.
You must match all the driver and output transistors. It's important. Buy only new. If you have bought NTE or ECG's, pitch them as they are hopeless. Give them to someone you don't like.
I'm going to bet the amp was oscillating and cooked itself to death. I found out about this from a repair. The channel powered up fine, bias and offset was stable so I went to get a coffee (Hey! I'm a technician, what else do you expect?). Coming back I could smell the heat, the scope had a fully lit screen from the rather strong oscillation. Pulling the caps and testing them, I found most were next to open. The point I'm making is that it may not break into oscillation right away.
If you use a variac to bring the voltage up slowly, you need to short the surge resistor out first.
-Chris
Gotcha. And thanks for the tip on those box caps, too. I was planning on using Toshiba B554 and D424 subs for the outputs, unless you have a better suggestion.
By the way, I dropped a few pennies in the "Begathon" - your help is greatly appreciated!!! 🙂
By the way, I dropped a few pennies in the "Begathon" - your help is greatly appreciated!!! 🙂
Hi dbp650,
As you know, I'm always happy to help. Thank you for helping the site, that was very nice of you. 🙂
I don't think the Toshiba transistors would be my first choice. I love those parts in some Marantz recievers and they were a stock part for me over many years.
Given that the power output stage is a stacked affair, speed may not help you here. I have used the MJ15022 and MJ15023 pairs with success before. These days I might be persuaded to try MJ21195 and MJ21196 out. These have a better SOA and more linear gain curve than the MJ15022 and MJ15023 types. They higher gain bandwidth product may cause some trouble, I don't know. It is possible you may need to play with the feedback compensation also.
Another thing to watch for. C309 is a 330 uF 6V capacitor in the feedback network (to signal ground). This cap tends to go open. I can't forget the first time a guy said his amp had no bass. It didn't. The cap was almost open. Replace with a voltage 35 ~ 50 V. The higher voltage cap has lower DA, you may be able to use a 470 uF if it fits.
Let me know how everything works out for you.
-Chris
As you know, I'm always happy to help. Thank you for helping the site, that was very nice of you. 🙂
I don't think the Toshiba transistors would be my first choice. I love those parts in some Marantz recievers and they were a stock part for me over many years.
Given that the power output stage is a stacked affair, speed may not help you here. I have used the MJ15022 and MJ15023 pairs with success before. These days I might be persuaded to try MJ21195 and MJ21196 out. These have a better SOA and more linear gain curve than the MJ15022 and MJ15023 types. They higher gain bandwidth product may cause some trouble, I don't know. It is possible you may need to play with the feedback compensation also.
Another thing to watch for. C309 is a 330 uF 6V capacitor in the feedback network (to signal ground). This cap tends to go open. I can't forget the first time a guy said his amp had no bass. It didn't. The cap was almost open. Replace with a voltage 35 ~ 50 V. The higher voltage cap has lower DA, you may be able to use a 470 uF if it fits.
Let me know how everything works out for you.
-Chris
Chris,
Just a follow-up for you (and a big apology to sound_prodigy for the huge threadjack!):
Got the 510M singin' tonight - finally. I went with MJ15024/5's on the main drivers - very similar to the MJ15022/3's, but able to handle a bit more current, according to the datasheets. I replaced master and slave drivers, and the zobel cap as well, based upon your recommendation. I went ahead and replaced all the box caps (they all tested within tolerance, but better safe than sorry) and stuffed a 470uF @ 35V in to replace C309.
Put her back together, shorted R3, brought her up slow on a variac, and immediately noted voltage on the speaker outputs. 🤐!! Pulled the driver board, and tracked the problem down to a B-E short in Q311, and a two shorted/leaky switching diodes (CR307 & 309).
Brought her back up slow, and no DC on the outputs! 🙂 Hooked up an input signal, and those big ol' meters jumped to life for the first time in probably quite a while. What a beautiful sight! I still have some fine tuning to do, but for tonight, I'm happy.
Couldn't have done it without you, Chris - thank you!!
Just a follow-up for you (and a big apology to sound_prodigy for the huge threadjack!):
Got the 510M singin' tonight - finally. I went with MJ15024/5's on the main drivers - very similar to the MJ15022/3's, but able to handle a bit more current, according to the datasheets. I replaced master and slave drivers, and the zobel cap as well, based upon your recommendation. I went ahead and replaced all the box caps (they all tested within tolerance, but better safe than sorry) and stuffed a 470uF @ 35V in to replace C309.
Put her back together, shorted R3, brought her up slow on a variac, and immediately noted voltage on the speaker outputs. 🤐!! Pulled the driver board, and tracked the problem down to a B-E short in Q311, and a two shorted/leaky switching diodes (CR307 & 309).
Brought her back up slow, and no DC on the outputs! 🙂 Hooked up an input signal, and those big ol' meters jumped to life for the first time in probably quite a while. What a beautiful sight! I still have some fine tuning to do, but for tonight, I'm happy.
Couldn't have done it without you, Chris - thank you!!
Hi dbp650,
Hey, you got it working. Good show.
Nothing seems to be straight forward, but you found the wrinkles. So, now the big question. How does it sound?
-Chris
Hey, you got it working. Good show.
Nothing seems to be straight forward, but you found the wrinkles. So, now the big question. How does it sound?
-Chris
That amp looks a lot like the inside of a XP550 but the ones I have use a 53-0-53 transformer. Mine have a sort of grainyness to the sound that is really anoying. If you figure out how to make them sound nice let me know.
John.....
John.....
Does the hiss depend on position of gain control knobs?
All of them have overrated voltage supply. Mine had 50-0-50 transformer, so excess of a voltage was used to shut down overload protection on the output power much less then rated. I replaced it with 37-0-37 and added couple more 10,000/63 caps, now it works well giving me fair 200W per channel on 4 Ohm loads.
whatsnext said:
All of them have overrated voltage supply. Mine had 50-0-50 transformer, so excess of a voltage was used to shut down overload protection on the output power much less then rated. I replaced it with 37-0-37 and added couple more 10,000/63 caps, now it works well giving me fair 200W per channel on 4 Ohm loads.
Wavebourn said:
So your xp550 and xp375 amps both use 50-0-50 transformers? GemSound must change their amps with some regularity.
whatsnext said:
xp550 on this photo uses even higher voltage! But less transistors... Mine has 3 of them per shoulder in each channel.
I was surprised, actually - the 510M has a warm, natural sound - quite a bit different from the Marantz 2500s I've listened to (the most similar amp section I could think of for comparison). To me, the Marantz 2500 has a somewhat harsh, almost "metallic" sound to it - I tend to fatigue very easily after 30 or 40 minutes of listening.anatech said:
It took me a while to get back to you, because once I set her up in my system and fired her up, I noticed the left meter was dead.
Popped he top and tapped the meter housing a few times, and it sprang to life - only to die a few minutes later.Turns out, after removing very carefully disassembling the meter in question, I discovered an internal lug fastened down by a Phillips screw that had come loose somehow. Tightened her up, and she's good as new. I'm a happy man! 🙂 Thanks again, Chris!!!
Hi dbp650,
The 2500 only shares the heatsink assembly with the 510. The amp circuits are completely different. The 2500 can be improved to sound nice. Watch the nylon (or whatever they are) spacers. They melt and release pressure on the outputs. Then they blow up due to overheating of the transistors themselves. I am trying to find a good solution for this.
-Chris
The 2500 only shares the heatsink assembly with the 510. The amp circuits are completely different. The 2500 can be improved to sound nice. Watch the nylon (or whatever they are) spacers. They melt and release pressure on the outputs. Then they blow up due to overheating of the transistors themselves. I am trying to find a good solution for this.
-Chris
sound_prodigy said:
maybe, save the power supply, and 'pass-i-fy'
the signal sections?
http://www.diyaudio.com/forums/forumdisplay.php?s=&forumid=8
If you had noise in one channel, I'd suspect a defective transistor or something (I had exactly that problem with a Hafler preamp). But, considering it claims to do over 700 watts into 4 ohms, maybe that's just the normal noise level. It's not like Gemsound actually claims to meet any s/n specifications. You should be grateful it doesn't just put out 700 watts of white noise and emit toxic levels of gamma radiation.
Use it as a sub amp, or sell it locally to some DJ, or use the parts to build something better.
Use it as a sub amp, or sell it locally to some DJ, or use the parts to build something better.
marantz 510m Cheap Gemsound Amplifier
From,
GUROL
HI MR CHRIS
MJ15024/5 TRANSISTORS -WHICH TRANSISTORS YOU CHANGE? S41775/S41776? OR SJ6206/SJ6207 ?
THANKS
Gurol
From,
GUROL
HI MR CHRIS
MJ15024/5 TRANSISTORS -WHICH TRANSISTORS YOU CHANGE? S41775/S41776? OR SJ6206/SJ6207 ?
THANKS
Gurol
Cheap Gemsound Amplifier Post #35
MARANTZ 510M
From,
GUROL
HI MR CHRIS
MJ15024/5 TRANSISTORS -WHICH TRANSISTORS YOU CHANGE? S41775/S41776? OR SJ6206/SJ6207 ?
THANKS
Gurol
MARANTZ 510M
From,
GUROL
HI MR CHRIS
MJ15024/5 TRANSISTORS -WHICH TRANSISTORS YOU CHANGE? S41775/S41776? OR SJ6206/SJ6207 ?
THANKS
Gurol
Hi Gurol,
Sorry, I don't understand your question really.
There is nothing wrong with the original transistors as long as they haven't blown. If they have, you would replace the set on that channel.
Also, please turn your caps lock key off and use the shift kep for the odd capital.
-Chris
Sorry, I don't understand your question really.
There is nothing wrong with the original transistors as long as they haven't blown. If they have, you would replace the set on that channel.
Also, please turn your caps lock key off and use the shift kep for the odd capital.
-Chris
HI MR CHRIS
SORRY MY BAD ENGLISH.
YOU CAHNGE THE POWER TRANSISTORS TO YOUR MARANTZ 510M?
WHICH TRANSISTORS FIT TO -S41775, S41776 ,SJ6207,SJ6206 ?
AND WHICH CAPACITORS YOU CHANGE?
Thanks
Gurol
SORRY MY BAD ENGLISH.
YOU CAHNGE THE POWER TRANSISTORS TO YOUR MARANTZ 510M?
WHICH TRANSISTORS FIT TO -S41775, S41776 ,SJ6207,SJ6206 ?
AND WHICH CAPACITORS YOU CHANGE?
Thanks
Gurol
Hi Gurol,
The procedure is a bit much to explain. If you lose a power transistor, replace the entire set in that channel. It is necessary for you to match them for gain. The manual is very clear on this.
You may be further ahead to have an experienced, good audio technician work on it for you. In my experience, television technicians don't have the proper experience or thinking to do good amplifier repairs. You need to use an audio technician, a good one. Everyone thinks they are a pro.
-Chris
The procedure is a bit much to explain. If you lose a power transistor, replace the entire set in that channel. It is necessary for you to match them for gain. The manual is very clear on this.
You may be further ahead to have an experienced, good audio technician work on it for you. In my experience, television technicians don't have the proper experience or thinking to do good amplifier repairs. You need to use an audio technician, a good one. Everyone thinks they are a pro.
-Chris
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